syzbot

==================================================================
BUG: KCSAN: data-race in serial8250_do_startup / serial8250_handle_irq

write to 0xffffffff86fb2a16 of 1 bytes by task 18822 on cpu 0:
 serial8250_do_startup+0x1272/0x1460 drivers/tty/serial/8250/8250_port.c:2459
 serial8250_startup+0x3b/0x40 drivers/tty/serial/8250/8250_port.c:2481
 uart_port_startup drivers/tty/serial/serial_core.c:289 [inline]
 uart_startup+0x3b0/0x690 drivers/tty/serial/serial_core.c:332
 uart_port_activate+0x66/0xb0 drivers/tty/serial/serial_core.c:1966
 tty_port_open+0x15f/0x1f0 drivers/tty/tty_port.c:784
 uart_open+0x30/0x40 drivers/tty/serial/serial_core.c:1946
 tty_open+0x3d3/0xb00 drivers/tty/tty_io.c:2154
 chrdev_open+0x34f/0x3c0 fs/char_dev.c:414
 do_dentry_open+0x5cd/0xaf0 fs/open.c:914
 vfs_open+0x4a/0x50 fs/open.c:1048
 do_open fs/namei.c:3636 [inline]
 path_openat+0x17f2/0x1d10 fs/namei.c:3793
 do_filp_open+0xf6/0x200 fs/namei.c:3820
 do_sys_openat2+0xab/0x110 fs/open.c:1407
 do_sys_open fs/open.c:1422 [inline]
 __do_sys_openat fs/open.c:1438 [inline]
 __se_sys_openat fs/open.c:1433 [inline]
 __x64_sys_openat+0xf3/0x120 fs/open.c:1433
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x41/0xc0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x63/0xcd

read to 0xffffffff86fb2a16 of 1 bytes by interrupt on cpu 1:
 serial8250_handle_irq+0x375/0x450 drivers/tty/serial/8250/8250_port.c:1941
 serial8250_default_handle_irq+0x8f/0x120 drivers/tty/serial/8250/8250_port.c:1963
 serial8250_interrupt+0x59/0x110 drivers/tty/serial/8250/8250_core.c:127
 __handle_irq_event_percpu+0x91/0x490 kernel/irq/handle.c:158
 handle_irq_event_percpu kernel/irq/handle.c:193 [inline]
 handle_irq_event+0x64/0xf0 kernel/irq/handle.c:210
 handle_edge_irq+0x167/0x590 kernel/irq/chip.c:834
 generic_handle_irq_desc include/linux/irqdesc.h:161 [inline]
 handle_irq arch/x86/kernel/irq.c:238 [inline]
 __common_interrupt+0x3c/0xb0 arch/x86/kernel/irq.c:257
 common_interrupt+0x7a/0x90 arch/x86/kernel/irq.c:247
 asm_common_interrupt+0x26/0x40 arch/x86/include/asm/idtentry.h:636
 find_watchpoint kernel/kcsan/core.c:120 [inline]
 check_access kernel/kcsan/core.c:737 [inline]
 __tsan_read8+0x1d/0x180 kernel/kcsan/core.c:1025
 vm_normal_page+0x83/0x1a0 mm/memory.c:634
 copy_present_pte mm/memory.c:933 [inline]
 copy_pte_range mm/memory.c:1082 [inline]
 copy_pmd_range mm/memory.c:1167 [inline]
 copy_pud_range mm/memory.c:1204 [inline]
 copy_p4d_range mm/memory.c:1228 [inline]
 copy_page_range+0x992/0x2050 mm/memory.c:1326
 dup_mmap kernel/fork.c:758 [inline]
 dup_mm kernel/fork.c:1689 [inline]
 copy_mm+0x9da/0xff0 kernel/fork.c:1738
 copy_process+0x1008/0x2180 kernel/fork.c:2504
 kernel_clone+0x169/0x560 kernel/fork.c:2912
 __do_sys_clone kernel/fork.c:3055 [inline]
 __se_sys_clone kernel/fork.c:3039 [inline]
 __x64_sys_clone+0xe8/0x120 kernel/fork.c:3039
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x41/0xc0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x63/0xcd

value changed: 0x00 -> 0x05

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 12378 Comm: syz-executor.4 Not tainted 6.5.0-rc5-syzkaller-00053-g13b937206866 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/26/2023
==================================================================